A projection device, such as a projector, provides an illumination light beam via an illumination system, then converts the illumination light beam to an image light beam via a light valve, and projects the image light beam onto a projection screen via a projection lens, so as to display an image on the projection screen.
In order to place the components of the projection device properly, in the conventional techniques, a reflective element is used to adjust a transmission path of the illumination light beam. The reflective element is usually fixed to an adjusting apparatus for fine adjustment of a placement angle of the reflective element to effectively correct optical path errors which is caused by assembly tolerances. The optical path is the transmission path of the illumination light beam and/or the image light beam. Some patents or patent application publications disclose the adjusting apparatus for supporting a reflective element, such as U.S. Pat. No. 7,871,167, China patent No. CN2305687Y and China patent application publication No. CN100589023 C.
However, the conventional adjusting apparatus can only rotate the reflective element within a fixed range of angles in 2-axis directions. For example, the reflective element can only be rotated with respect to a horizontal axis and a vertical axis which are respectively parallel to a long side and a short side of a reflective surface of the reflective element, thereby limiting improvement effect of correction of the optical path errors.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art.